А) (5с+4)^2/(35c^2+28c)=(5с+4)²/[7с(5с+4)]=(5c+4)/7c
б)( x^3+27y^3)/(9y^2-3xy+x^2)=(x+3y)(x²-3xy+9y²)/(9y²-3xy+x²)=(x+3y)
в)( 5m^2+15mn)/(m+3n)=5m(m+3n)/(m+3n)=5m
а) (x+6)/(x+1)-(x-6)/(x-1)=(x²-x+6x-6-x²-x+6x+6)/(x²-1)=10x/(x²-1)
б) 3/(b^2-3b)+1/(3-b)=3/b(b-3)-1/(b-3)=(3-b)/b(b-3)=-1/b
в) (2c+1)-(5c^2-1)/(2c-1)=(4c²-1-5c²+1)/(2c-1)=-c²/(2c-1)=c²/(1-2c)
г) a^2/(a^3-9a)-1/(2a-6
)=a²/[a(a-3)(a+3)]-1/[2(a-3)]=
=a/[(a-3)(a+3)]-1/[2(a-3)]=(2a-a-3)/[2(a²-9)]=(a-3)/[2(a-3)(a+3)]=1/[2(a+3)]